/*
             LUFA Library
     Copyright (C) Dean Camera, 2009.
              
  dean [at] fourwalledcubicle [dot] com
      www.fourwalledcubicle.com
*/

/*
  Copyright 2009  Dean Camera (dean [at] fourwalledcubicle [dot] com)

  Permission to use, copy, modify, and distribute this software
  and its documentation for any purpose and without fee is hereby
  granted, provided that the above copyright notice appear in all
  copies and that both that the copyright notice and this
  permission notice and warranty disclaimer appear in supporting
  documentation, and that the name of the author not be used in
  advertising or publicity pertaining to distribution of the
  software without specific, written prior permission.

  The author disclaim all warranties with regard to this
  software, including all implied warranties of merchantability
  and fitness.  In no event shall the author be liable for any
  special, indirect or consequential damages or any damages
  whatsoever resulting from loss of use, data or profits, whether
  in an action of contract, negligence or other tortious action,
  arising out of or in connection with the use or performance of
  this software.
*/

/** \file
 *
 *  User Datagram Protocol (UDP) packet handling routines. This protocol handles high throughput, low
 *  reliability packets which are typically used to encapsulate streaming data.
 */
 
#define  INCLUDE_FROM_UDP_C
#include "UDP.h"

/** Processes a UDP packet inside an Ethernet frame, and writes the appropriate response
 *  to the output Ethernet frame if a subprotocol handler has created a response packet.
 *
 *  \param IPHeaderInStart    Pointer to the start of the incoming packet's IP header
 *  \param UDPHeaderInStart   Pointer to the start of the incoming packet's UDP header
 *  \param UDPHeaderOutStart  Pointer to the start of the outgoing packet's UDP header
 *
 *  \return The number of bytes written to the out Ethernet frame if any, NO_RESPONSE otherwise
 */
int16_t UDP_ProcessUDPPacket(void* IPHeaderInStart, void* UDPHeaderInStart, void* UDPHeaderOutStart)
{
	UDP_Header_t* UDPHeaderIN  = (UDP_Header_t*)UDPHeaderInStart;
	UDP_Header_t* UDPHeaderOUT = (UDP_Header_t*)UDPHeaderOutStart;
	
	int16_t RetSize = NO_RESPONSE;
	
	DecodeUDPHeader(UDPHeaderInStart);
	
	/* Check to see if the UDP packet is a DHCP packet */
	if (SwapEndian_16(UDPHeaderIN->DestinationPort) == UDP_PORT_DHCP_REQUEST)
	{
		RetSize = DHCP_ProcessDHCPPacket(IPHeaderInStart,
		                                 &((uint8_t*)UDPHeaderInStart)[sizeof(UDP_Header_t)],
	                                     &((uint8_t*)UDPHeaderOutStart)[sizeof(UDP_Header_t)]);
	}
	
	/* Check to see if the protocol processing routine has filled out a response */
	if (RetSize > 0)
	{
		/* Fill out the response UDP packet header */
		UDPHeaderOUT->SourcePort      = UDPHeaderIN->DestinationPort;
		UDPHeaderOUT->DestinationPort = UDPHeaderIN->SourcePort;
		UDPHeaderOUT->Checksum        = 0;
		UDPHeaderOUT->Length          = SwapEndian_16(sizeof(UDP_Header_t) + RetSize);

		/* Return the size of the response so far */
		return (sizeof(UDP_Header_t) + RetSize);
	}
	
	return NO_RESPONSE;
}
